Radio receiving antenna circuit



Aug. 18, 1936.

L. J. LESH RADIO RECEIVING ANTENNA CIRCUIT Filed June 18, 1934 Patentedug. 18, Q

UNITED STATES PATENT OFFICE Y 2,051,260 RADIO RECEIVING ANTENNA CIRCUITApplication June 1s, 1934, serial No. 731,025

.4 Claims.

My invention relates in general to improved radio receiving antennacircuits, and more specically to an improved circuit arrangement andinterconnection of radio receiving antenna the object of which is toimprove the selectivity thereof and to neutralize or reject interferingWaves and prevent them from interfering with the Wanted signals.

In order to attain this object I have shown as an example one circuitarrangement having various devices shown in proper relationship andadjustable to meet various conditions. In general the arrangement shownconsists of a plurality of antenna branches, connected together at acommon point. One branch has the radio receiving set coupled thereto inthe usual manner, while the other branches include suitab-le variablesof resistance, capacity and inductance with ground shunts therefromthrough variable resistances. The arrangement shown may be utilized toneutralize or reject interfering waves from Various sources and I haveshown the method of neutralizing interference emanating from a telephoneline by substituting a telephone circuit for one of the antennabranches. It will be understood that interference may arise from variouscauses such as electrical machinery, power lines and such interferencemay arise from devices located at various points relative to the radiocircuit. Therefore I have shown certain connecting switches in thedrawing for cutting out or switching certain of the elements in order tomeet the requirements of a particular instance. In other words, forcertain interfering waves it may be found necessary to disconnectcertain or all of the ground shunts while in other instances it will befound preferable to close such shunts.

In the accompanying drawing consisting of a single iigure I have shownthree branched antenna circuits converging at a common point designatedat X. The antenna branch A includes a suitable coupling L L4 to theradio receiving set RR, this coupling and also the radio receiving setmay be of any commonly used type although I prefer a coupling of theinductive type to an ungrounded receiving set. The branch antenna A2 hasin series therewith a resonant circuit including inductance L2, capacityC2 and resistance R1, adjustable to the received frequency. Thisresonant circuit is connected to ground through a variable resistance R5and a disconnecting switch SW2. In addition branch A2 is connected tothe arm of switch SW1 through which this branch may be connected to thean- (Cl. Z50-20) shunt condenser C4. The line 'IL is, of course, 5

bridged by the usual substation instrument circuit including talking andlistening instrumentalities as indicated at T. In use the telephone linewhen connected to this circuit acts as one of the antenna branches andis Substituted for branch A4. Branch antenna A3 has in series therewithanother resonant circuit comprising either a variable resistance R4 anda variable capacity C3 or the variable inductance L3 with the capacityC3 Adependent on the posi- 15 tion of a switch SW3. In addition to theresonant circuit this antenna branch A3v also has a shunt to groundthrough a disconnecting switch SW4 and a variable resistance R6.

The variable shunt resistances involved should be variable from 0 to1,000,000 ohms non-inductive resistance, while the inductancescapacities and resistances in the resonant circuits will be chosen invalues appropriate to the frequency of the received radio signals andsuch values are Well known to those conversant to the art.`

It is desirable to have the antenna branches of the same effectiveelectrical length and to have these branches arranged symmetrically inthe same plane although the physical arrangement admits of widevariation. It is also desirable to have variable coupling between theinductances L2 and L3 in the two resonant circuits.

By a proper selection and adjustment of the various components of thisarrangement it has been found possible to effectively neutralize oreliminate from the radio receiving set the interference emanating from anearby source, of a magnitude comparable with the incoming radio Waves.This neutralization permits clear and undisturbed reception of a desiredradio signal under conditions where reception by a simple radio antennais impossible. It has been found possible to completely balance out thebeat or heterodyne note produced by an oscillator in the vicinity of theradio receiver against an incoming radio carrier wave, under conditionswhere conventional set-ups would render reception impossible. It hasalso been found that proper adjustments of the components of my improvedantenna system will also demonstrate useful directive sensitivity andsensibility.

It will be understood that in practice the selection and adjustments ofthe antenna components is determined by tests to meet the con- In thisinstance, space limitation dictated thatl the antenna arms A1 and A2 ofmy arrangement be not longer than ten feet {andthat they be placedalmost parallel and about two feet apart. Under these conditions it wasfound by experiment that the best results were obtained by closingswitch SWl to branch A4, closing switch'SWZ' so that a shunt to groundof about 100,000 ohms resistance was obtained,closing switch SW3 toconnect up inductance L3, and closing switch SW4 and adjustingresistance R6 tominimize resistance or direct to ground. The variablercornponents were then adjusted until interference was eliminated andsatisfactory radio reception was provided at the desired wave length.

Having described the general arrangement and features 4of my invention,what I consider to be novel and desire to have protected by LettersPatent'will be pointed out in the appended claims.

What is claimed is: y 1. A radio receiving antenna system comprising aplurality of antenna branches connected ktogether at a common point, aradio receiver coupled to one branch, Aa telephone circuit included inanother branch together with means ditions imposed by local conditionssuch as the for controlling the resonance and phase thereof at radiofrequency, and phase and resonance control means included in a third oneof saidV branches.

2. In a radio receiving antenna system, .a plurality of antenna branchesradiating from a common point, a radio receiving set coupled to oneponents and shunts adjustable to eliminate interference in the receivingset due to oscillations "from an interfering source.

3. Ina radio receiving antenna system, a plurality of antennas, acircuit .connecting one antenna to a common point, a radio receiving setcoupled to said circuit between the antenna and the common point, acircuit connecting each of the other antennas to the common point, aresonant circuit in each of said other circuits between the respectiveantennas vand the common point, and circuits for connecting each of saidother antennas to ground through a variable resistance independent ofsaid resonant circuits.

ll. In a radio receiving antenna system, a pair of antenna branchesconnected together at a common point, each branch connected to thecommon point through a resonant circuit having means for controlling theresonance and phase thereof, a telephone circuit also connected to saidcommon point through a similar resonance circuit, a variable groundshunt for said telephone circuit, and a radio receiving set coupled toone of said branches.

' LAURENCE J LESI-I.

